1. Field of the Invention
The present invention relates to a signal shielding box, and in particular to a signal shielding box which is used to measure a wireless communication device and has a plurality of shielding covers.
2. Description of Related Art
Electronic devices during research period or before shipping should be subjected to measurement within electromagnetic interference (EMI) environment so as to be compatible with specific requirement. The electronic devices are usually subjected to measurement within a separated environment such as electromagnetic shielding room worth of tens of millions NT dollars or signal shielding box.
FIG. 1 illustrates a schematic of signal shielding box in prior art and is a representative drawing of Taiwan Patent No. M294830. A shielding cover 2 (pivotal cover) is rotatably connected with a shielding box 1 (shielding housing), and the shielding cover 2 is supported by resilient rod 21. The electronic device 5 is placed within a receiving space 11 of the shielding box 1 so that the electronic device 5 is subjected to measurement.
However, only one pivotal cover (shielding cover 2) is utilized in prior art, and the electronic device 5 is subjected to measurement under fully opened and fully closed environments. It fails to simulate practical environment when the electronic devices are in used. When wireless communication devices move within mobile environment, strength change of signals is complicated. For example, strength of signal is changing, and execution procedure of software is problematic when base station is re-connected with the wireless communication device. Thus, we need to confirm whether gain of receiver/transmitter antenna is proper and execution procedure of software is normal. It needs simulation of measurement under various environments (a plurality of shielding effects).
In addition, the signal shielding box in prior art needs much more space above the signal shielding box when the shielding cover 2 is opened by the resilient rod 21. The shielding cover 2 is rotatably connected with the shielding box 1 and heavy-weighted to effectively shield electromagnetic wave so it is not convenient to open the shielding cover 2 by an electrical motor but manually. The resilient rod 21 is needed to support opening or closing the shielding cover 2.
When the electronic devices are subjected to measurement, the shielding cover 2 may be opened and closed hundred times or even tens of thousands times manually. It is tiresome for test personals to open and close tens of thousands times manually. In addition, the signal shielding box is unlikely compatible with automatic design if it is not convenient to open or close the shielding cover 2 by the electrical motor. In this light, the electronic devices cannot be measured under a variety of environments (shielding effects) by automatically controlling the shielding cover 2.
As to measurement of wireless communication devices described above, the signal shielding box in prior art is not properly utilized.
Thus, there is a need for a signal shielding box which is used to measure a wireless communication device and has a plurality of shielding covers to overcome above disadvantages.